Ignition distributor with control generator for internal combustion engines

ABSTRACT

The minimal clearances between the pole teeth of the stator and rotor of the control generator in an ignition distributor for internal combustion engines are independent of eventual stray movements of the drive shaft by mounting the stator on the drive shaft so that the stator and the rotor of the control generator share all stray movements of the drive shaft but the rotor is free to rotate, without contact, relative to the stator. The stator is angularly adjustable with reference to the drive shaft by a link which changes its position in response to pressure changes in the intake manifold of the internal combustion engine. The drive shaft has a male portion which is journalled in the housing of the ignition distributor and a sleeve which is rotatably mounted on the male portion and supports the stator and the rotor of the control generator. The sleeve receives torque from the male portion by means of a centrifugal advance mechanism. The entire rotor, portions of the rotor, and/or portions of the stator can be made of a sintered material.

United States Patent 1191 Brammer et al.

nn 3,744,466 1 1' July 10, 1973 IGNITION DISTRIBUTOR WITH CONTROLGENERATOR FOR INTERNAL COMBUSTION ENGINES [75] Inventors: HartmutBrammer, Stuttgart; Gerd Hiihne, Ludwigsburg; Gert Jakob,

Stuttgart; Harald Kalippke, Hohenacker'; Gerhard Siilmer, Geradstetten;Karl Ehrmann;

Giinter Brand, both of Stuttgart, all

of Germany [73] Assignee: Bosch GmbII, Stuttgart, Germany 22] Filed:July 16,1971

21 App1.No.: 163,374 1 [3011 Foreign/Application Priority Data July 31.,1970 Gennany P 20 38 037.4

. 521 vs. (11...... 123/148 1:, 123/148 R 51 1m. (:1 F02p 1 00 58] Fieldof Search 123/148 E [56] References Cited UNITED STATES PATENTS3,554,117 111971 Hufton 123/148 3,620,200 l1/l97l Stephens... 123/1483,621,826 11/1971 Chrestensen 123/148 FOREIGN PATENTS OR' APPLICATIONS1,137,949 12/1955 France 123/148 1,319,022 4/1962 France. ..123/148358,283 12/1959 Switzerland 123/148 Primary Examiner-Laurence M.Goodridge I Assistant Examiner-RonaldB. Cox Attorney-Michael S. Striker51 ABSTRACT" The minimal clearances between the pole teeth of th statorand rotor of the control generator in an ignition distributor forinternal combustion engines are independent of eventual stray movementsof the drive shaft by mounting the stator on the drive shaft so that thestator and the rotor of the control generator share all stray movementsof the drive shaftbut the rotor is free to rotate, without contact,relative to the stator. The'stator is angularly adjustable withreference to the drive shaft bya link which changes its position inresponse to pressure changes in the intake manifold of the internalcombustion engine. The drive shaft has a male portion which isjournalled in the housing of the ignition distributor and a sleevewhich-is rotatably mounted on the male portion and supports the statorand the rotor of the control generator. The sleeve receives torque fromthe male portion by means of a centrifugal advance mechanism. The entirerotor, portions of the rotor, and/or portions of the stator can be madeof a sintered material. g

15 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION The presentinvention relates to ignition distributors for internal combustionengines, and more particularly to improvements in ignition distributorsof the type having a magnetic control generator.

It is already known to provide an ignition distributor for internalcombustion engines with a control genera-- tor which is built into thehousing of the ignition distributor and serves to furnish to anelectronic switching element high-voltage impulses at the time of firingof the spark plugs. As a rule, the control generator comprises a statorwhich is fixedly or adjustably secured to the housing of the ignitiondistributor and a rotor which is rotated by the drive shaft of theignition distributor. The control generator must furnish voltageimpulses at the time when the engine operates at normal speed as well asduring idling of the engine. Even those voltage impulses which aregenerated during idling of the engine must exceed the voltage-at whichthe electronic switching element responds to thus insure the generationof voltage which suffices for the firing of spark plugs. The intensityof impulses furnished by the control generator is a function of thespeed and extent of variations of magnetic flux which influence theinduction coil of the generator, and the extent of such variations is afunction of the magnitude of working clearance or gap between the statorand rotor of the control generator.

In presently known ignition distributors which embody controlgenerators, the clearance between the relatively movable parts of thestator and rotor in the control generator cannot be reduced beyond acertain value because the stator is either fixedly or adjustably'mounted in the housing of the ignition distributor whereas the rotor ofthe control generator rotates with the drive shaft. Therefore, the rotorshares all axial, wobbling and/or other stray movements of the driveshaft and the clearance between the rotor and the stator must be largeenough to account for eventual stray movements of the drive shaft withreference to the housing of the ignition distributor (and hence withreference to the stator). In other words, the clearance between therotor and the stator must be much larger than would be absolutelynecessary to avoid contact between the rotor and the stator if the rotorwere compelled to remain at all times in exact axial alignment with thestator. Therefore, the reduction of clearance between the stator androtor of a conventional control generator can be achieved only bymachining the parts of the ignition distributor with a very high degreeof precision so as to reduce stray movements of the drive shaft and ofthe rotor with reference to the housing of the ignition distributor andthe stator of the control generator. This obviously involves a muchhigher manufacturingcost; furthermore, some stray movements will developwithout fail on prolonged use of the ignition distributor.

SUMMARY OF THE INVENTION An object of the invention is to provide anignition distributor for internal combustion engines wherein the minimumclearances between the stator and rotor of the built-in controlgenerator can be much smaller than in presently known ignitiondistributors without necessitating a higher precision in the manufactureof component parts. 7

Another object of the invention is to provide a novel and improvedmounting for the stator of the control generator in an ignitiondistributor for internal combustion engines. i

A further object of the invention is to provide a control generatorwherein the clearances between the stator and the rotor are not affectedby eventual axial, wobbling and/or other stray movements of the rotorwith reference to the housing of the ignition distributor.

An additional object of the invention is to provide an ignitiondistributor wherein the stator of the control generator is mounted inthe above outlined manner and can be adjusted to account for changes inthe load upon the engine.

Still another object of the invention is to provide a novel and improvedcontrol generator which can be built into presently known ignitiondistributors by necessitating relatively minor changes in the design ofsuch distributors. I

A further object of the invention is to provide a control'generatorwhich, even though not larger than presently known control generators,canproduce impulses of greater intensity not only when the engine isoperated at a high RPM but also at the idling speed of the engine.

The invention resides in an ignition distributor for internal combustionengines which comprises a housing, a drive shaft which is rotatable inthe housing and preferably includes a male portion which is directlyjournalled in the housing and a female portion or sleeve which surroundsthe male portion and is coupled thereto by a centrifugal advancemechanism, and a magnetic control generator which has a rotor fixedlysecured to'the sleeve and a stator which is closely adjacent to but outof contact with the rotor and is mounted on the sleeve in such a waythat the sleeve is rotatable with the rotor relative to the stator butthat the stator shares all eventual stray movements of the sleeve withreference to the male portion of the drive shaft and/or with referenceto the housing. Thus, all stray movements of the sleeve (such as axialdisplacements and/or wobbling on the male portion of the drive shaft)are shared by the stator as well as by the rotor whereby the minimumclearances between the stator and the rotor remain unchanged.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved ignition distributor itself, however, both as to itsconstruction and its mode of operation, together with additionalfeatures and advantages thereof, will be best understood upon perusal ofthe following detailed description of certain specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a'central vertical sectionalview of an ignition distributor which embodies the invention, the sec- 4tion being taken in the direction of arrows as seen from the line I-I ofFIG. 2; and

' '-FIG. 2 is a horizontal sectional view of the ignition DESCRIPTION OFTHE PREFERRED EMBODIMENTS Referring first to FIG. 1, there is shown anignition distributor for a six-cylinder internal combustion engine. Theignition distributor 10 comprises a'housing having a base assembly 11with a sleeve 11a and a cap provided with a center electrode 21 and sixequidistant distributorelectordes 22. The sleeve 11a of the baseassembly 11 surrounds a two-piece drive shaft 12 which is rotated by theinternal combustion engine, not shown.

The lower portion of the base assembly 11 accommodates a centrifugaladvance mechanism 13 which has a weight base 14 secured to the maleportion 12a of the drive shaft 12 and supporting two advance weights 16(one shown) mounted on pivot pins 15. The advance cam 17 of themechanism 13 is secured to a female por tion or sleeve 18 of the driveshaft 12 which surrounds the male portion 12a. The advance weights 16are mounted diametrically opposite each other. The mechanism 13 couplesthe sleeve 18 for rotation with the male portion 12a.

The sleeve 18 supports a distributor rotor 19 which is surrounded by thecap 20 of the distributor housing and serves to transmit ignitionimpulses from an ignition coil (not shown) connected with the centerelectrode 21 'to successive distributor electrodes 22. The electrodes 22are connected with the spark plugs (not shown) of the internalcombustion engine.

The base assembly 11 of the distributor housing further surrounds anovel control generator 23 which is mounted between the distributorrotor 19 and the centrifugal advance mechanism 13. The control generator23 serves to produce a voltage impulse at the time of firing of sparkplugs; such impulses serve to control an electronic switching element(not shown) to thus initiate the release of high-voltage impulses in theignition coil.

The control generator 23 comprises a rotor 25 which is secured to thesleeve 18 for rotation therewith and a stator 24 which rotatablysurrounds the sleeve 18. The stator 24 comprises a disk-shaped support26 and a ring-shaped permanent magnet 27 which is magnetized in theaxial direction. The lower end face of the permanent magnet 27 abutsagainst the upper side of the support 26 and its upper end surfacecarries a ringshaped pole shoe 28 having an upwardly extendingcylindrical extension or collar 28a. The latter is surrounded by anannular induction coil 29 which is mounted in a frame 30 consisting ofsynthetic plastic material. The frame 30 is secured to the support 26 ofthe stator 24 by one or more screws 31 or analogous fasteners; thesefasteners simultaneously hold the permanent magnet 27 and the pole shoe28 against movement with reference to the support 26.

The stator 24 further includes a bearing sleeve or muff 32 which snuglysurrounds a median portion of the sleeve 18. The muff 32 consists ofnonferrous material, preferably a sintered material. Such material ispermeated with oil or another lubricant and the muff 32 is a press-fitin the axial passage or bore 33 of the support 26. The lower end face ofthe muff 32 abuts against a split ring 34 which is recessed into acircumferential groove of the sleeve 18.

The support 26 of the stator 24 is further provided with a radialyextending elongated opening or slot 47 for the stem of a coupling boltor projection 35 which extends into the slot 47 from below and isriveted to an intermediate portion of a motion transmitting ordisplacing link 36. As shown in FIG. 2, one end portion of the link 36extends into an adjusting device 37 and is attached therein to adiaphragm (not shown). The adjusting device 37 is fixedly secured to thebase assembly 11 of the distributor housing by a bracket 37a and screws37b. The other end portion 360 of the link 36 is reciprocable in a guideportion 48 provided on the internal surface of the base assembly 11. Theadjusting device 37 is connected with the intake manifold (not shown) ofthe engine by two flexible conduits 38 and 39, for example, in a mannerasdisclosed in the copending application Ser. No. 787,021 of HaraldKalippke et al. The diaphragm .in the adjusting device 37 is flexed inresponse to pressure changes in the intake manifold whereby the link 36moves lengthwise and changes the angular position of the stator 24 withreference to the sleeve 18. Since the end portion 36a of the link 36extends into the guide portion48 and the stem of the coupling bolt 35extends into the radial slot 47 of the support 26, axial-movements ofthe control generator 23 cannot bring about any changes in the positionof the link 36.

The periphery of the support 26 is provided'with six equidistantupwardly bent pole teeth 40 which are outwardly adjacent to thepermanent magnet 27, pole shoe 28, coil 29 and frame 30. The teeth 40cooperate with six equidistant pole teeth 41 of the rotor 25. The latterfurther comprises a disk-shaped portion 42 which is provided with theteeth 41, and a hollow shaft 43. The teeth 41 extend radially outwardlyfrom the disk 42. The minimum clearance 46 between the teeth 40 'and 41of the stator 24 and rotor 25 is 0.35 millimeters. The hollow shaft 43of the rotor25 abuts against the upper end face 32b of the mufi 32 andis held against rotation with reference to the sleeve 18 by means of anaxially parallel coupling pin 44 which extends into registering recessesof the parts 18 and 43. Thus, when the male portion 12a of the driveshaft 12 rotates, the sleeve 18 is rotated by the centrifugal advancemechanism 13 and the rotor 25 shares the rotary movement of the sleeve18 due to the provision of coupling pin 44. The upper end face of theshaft 43 abuts against a split ring 45 which is recessed into acircumferential groove of the sleeve 18.

The collar 28a of the pole shoe 28 is concentric with and surrounds theshaft 43 of the rotor 25 with a minimal radial clearance, e.g., in therange of 0.2 millimeters. The magnetic force lines issuing from thepennanent magnet 27 pass through the pole shoe 28, collar 28a, acrossthe annular clearance between the parts 28a, 43, through the hollowshaft 43 and into the diskshaped portion 42. The magnetic force linespass radially outwardly through the portion 42 and its teeth 41, acrossthe clearances 46 between the teeth 41 and 40, through the support 26and back to the permanent magnet 27. Thus, the annular coil 29 whichsurrounds the collar 28a of the pole shoe 28 is interlinked with theentire flow of magnetic force lines.

When the internal combustion engine is in operation, the male portion12a of the drive shaft 12 rotates the sleeve 18 through the intermediaryof the centrifugal advance mechanism 13. At the same time, the stator 24is held against rotation with the sleeve 18 by the link 36 so that thesleeve 18 rotates in the muff 32. Thus, the distributor rotor 19 rotateswith the rotor 25 of the control generator 23 whereby the teeth 41 ofthe diskshaped portion shown in the rotor 25 rotate with reference tothe teeth 40 on the support 26 of the stator 24. The distance betweenthe teeth 40, 41 varies continuously when the rotor 25 is driven by thesleeve 18 because the teeth 41 first approach and thereupon move awayfrom the teeth 40. Such changes in the width of clearances between theteeth 40, 41 entail corresponding changes in magnetic resistance andflux in the magnetic circuit of the control generator 23. The change influx reaches its maximum value when the teeth 41 are nearest to theteeth 40 (see the position of the rotor 25 as shown in FIG. 2). Suchchanges in flux induce in the coil 29 two voltage impulses one of whichis used for actuation of an electronic switching element to produce aspark at one of the spark plugs. Since the stator 24 has six teeth 40and the rotor 25 has six teeth 41, the induced voltage impulses in thecoil 29 cause the firing of six spark plugs during each revolution ofthe sleeve 18.

The timing of sparks can be advanced in dependency on the RPM 0f theengine by way of the centrifugal advance mechanism 13, Le, in responseto pivoting of advance weights 16 on their pins 12 whereby the advancecam 17 turns the sleeve 18 and the rotor 25 in the direction of rotationof the male portion 12a of the drive shaft 12. An adjustment of thetiming of spark generation in dependency on pressure changes in theintake manifold of the engine (and hence in dependency on the load uponthe engine) is effected by the link 36 which can change the angularposition of the stator 24 with reference to the sleeve 18.

In accordance with a slight modification of the illustrated embodiment,the entire rotor 25 can be made of a single piece of sintered iron.Also, the parts 26, 32, 28 and 28a can be made of a single piece ofsintered iron. This further reduces the tolerances in the dimensioningof minimum clearances 46 between the teeth 40 of the stator 24 and theteeth 41 of the rotor 25.

An important advantage of the improved ignition distributor is that thestator 24 of the control generator 23 is rotatable with reference to thesleeve 18 (i.e., that the sleeve 18 can rotate in the stator 24) withoutany appreciable clearance. Thus, the bearing sleeve or muff 32 (whichcannot move axially of the sleeve 18 and is a press-fit in the support26 of the stator 24) compels the stator to share all axial and/orwobbling movements of the sleeve 18. Since the rotor 25 is fixedlysecured to the sleeve 18, the minimum clearances 46'between the teeth 40and 41 are not affected by eventual axial, wobbling and/or other straymovements of the sleeve 18 with reference to the male portion 120 of thedrive shaft 12. Consequently, the minimum width of the clearances 46remains unchanged and such clearances can be much smaller than inconventional ignition distributors wherein the stator of the controlgenerator is affixed to the housing of the ignition distributor or isadjustably supported by such housing so that it can change its positionin response to pressure changes in the intake manifold of the engine.

Relatively small clearances 46 between the teeth 40 and 41 insure thatthe control impulses of the generator 23 are stronger than thoseproduced by conventional generators of identical dimensions. If desired,the rotor 25 can be mounted directly on the male portion of the driveshaft 12 and the latter is then rotatable directly in the bearing sleeveor muff 32 for the stator 24. Such simplified construction can beresorted to if the sleeve 18 and the centrifugal advance mechanism 13are omitted.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic -andspecific aspects of our contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected byvLetters Patent isset forth in the appended claims:

1. In an ignition distributor for internal combustion engines, acombinationcomprising a housing; a drive shaft comprising only a firstand a second portion, only said first portion being rotatably joumalledin said housing and said second portion rotatably surrounding said firstportion and projecting freely into said housing; a centrifugal advancemechanism coupling said second portion for rotation with said firstportion; and a magnetic control generator including a rotor secured tosaid second portion for rotation therewith, and a stator closelyadjacent to but out of contact with said rotor and comprising a supporthaving an axial bore and a bearing sleeve press-fitted in said bore andsnugly surrounding said second portion of said drive shaft so that saiddrive shaft is rotatable in said stator and said stator shares alleventual stray movements of the driveshaft, and hence of said rotor,with reference to said housing.

2. A combination as defined in claim 1, wherein said bearing sleeveconsists of sintered material.

3. A combination as defined in claim 1, wherein said bearing sleeve andsaid support consisting of sintered material. i

4. A combination as defined in claim 1, wherein said bearing sleeveconsists of sintered material which is permeated with a lubricant.

5. A combination as defined in claim 1, wherein said support and saidbearing sleeve consisting of a sintered material and said bearingsleevebeing permeated with a lubricant.

6. A combination as defined in claim 1, wherein said I rotor comprises ahollow shaft surrounding said second portion of said drive shaft, a diskrigid with said hollow shaft, and pole teeth extending radiallyoutwardly from said disk, said hollow shaft and said bearing sleevehaving abutting end faces and further comprising means for coupling saidhollow shaft to said second portion of said drive shaft so that saidrotor shares all movements of said second portion. A

7. A combination as defined in claim 1, wherein at least a portion ofsaid rotor consists of a sintered material.

8. A combination as defined in claim 1, wherein said stator furthercomprises an axially magnetized ringshaped permanent magnet on saidsupport, said permanent magnet surrounding said bearing sleeve andhaving an end face remote from said support and provided with aring-shaped pole shoe.

9. A combination as defined in claim 8, wherein said rotor comprises ahollow shaft surroudning said drive shaft and said pole shoe comprises acylindrical extension surrounding said hollow shaft.

10. A combination as defined in claim 8, wherein said pole shoe consistsof sintered material.

11. A combination as defined in claim 1, furthercomprising means forangularly adjusting said stator with reference to said drive shaft inresponse to pressure changes in the intake manifold of the engine.

12. A combination as defined in claim 11, wherein said adjusting meanscomprises a link which is arranged to move lengthwise in response topressure changes in the intake manifold.

said guide means.

I i i i i

1. In an ignition distributor for internal combustion engines, acombination comprising a housing; a drive shaft comprising only a firstand a second portion, only said first portion being rotatabLy journalledin said housing and said second portion rotatably surrounding said firstportion and projecting freely into said housing; a centrifugal advancemechanism coupling said second portion for rotation with said firstportion; and a magnetic control generator including a rotor secured tosaid second portion for rotation therewith, and a stator closelyadjacent to but out of contact with said rotor and comprising a supporthaving an axial bore and a bearing sleeve press-fitted in said bore andsnugly surrounding said second portion of said drive shaft so that saiddrive shaft is rotatable in said stator and said stator shares alleventual stray movements of the drive shaft, and hence of said rotor,with reference to said housing.
 2. A combination as defined in claim 1,wherein said bearing sleeve consists of sintered material.
 3. Acombination as defined in claim 1, wherein said bearing sleeve and saidsupport consisting of sintered material.
 4. A combination as defined inclaim 1, wherein said bearing sleeve consists of sintered material whichis permeated with a lubricant.
 5. A combination as defined in claim 1,wherein said support and said bearing sleeve consisting of a sinteredmaterial and said bearing sleeve being permeated with a lubricant.
 6. Acombination as defined in claim 1, wherein said rotor comprises a hollowshaft surrounding said second portion of said drive shaft, a disk rigidwith said hollow shaft, and pole teeth extending radially outwardly fromsaid disk, said hollow shaft and said bearing sleeve having abutting endfaces and further comprising means for coupling said hollow shaft tosaid second portion of said drive shaft so that said rotor shares allmovements of said second portion.
 7. A combination as defined in claim1, wherein at least a portion of said rotor consists of a sinteredmaterial.
 8. A combination as defined in claim 1, wherein said statorfurther comprises an axially magnetized ring-shaped permanent magnet onsaid support, said permanent magnet surrounding said bearing sleeve andhaving an end face remote from said support and provided with aring-shaped pole shoe.
 9. A combination as defined in claim 8, whereinsaid rotor comprises a hollow shaft surrounding said drive shaft andsaid pole shoe comprises a cylindrical extension surrounding said hollowshaft.
 10. A combination as defined in claim 8, wherein said pole shoeconsists of sintered material.
 11. A combination as defined in claim 1,further comprising means for angularly adjusting said stator withreference to said drive shaft in response to pressure changes in theintake manifold of the engine.
 12. A combination as defined in claim 11,wherein said adjusting means comprises a link which is arranged to movelengthwise in response to pressure changes in the intake manifold.
 13. Acombination as defined in claim 12, wherein said stator comprises asupport having an opening and said link comprises a projection extendinginto said opening.
 14. A combination as defined in claim 13, whereinsaid opening is an elongated slot extending substantially radially ofsaid drive shaft.
 15. A combination as defined in claim 12, wherein saidhousing is provided with internal guide means and said link has an endportion reciprocably received in said guide means.